The extant literature suggests that neighborhood characteristics shape risk of mobility limitation onset, yet there is relatively no research assessing whether neighborhood characteristics influence recovery from mobility limitation. This purpose of this research is twofold: 1) to identify and describe neighborhood characteristics which independently predict recovery from mobility limitation, net of individual-level characteristics; and 2) to determine whether participation in physical activity despite mobility limitation mediates or moderates the relationship between neighborhood characteristics and recovery. Data from the Health and Retirement Study (HRS) (2000-2008) will be utilized. The HRS is an ongoing, nationally-representative, longitudinal panel study of older Americans. Recovery from mobility limitations will be assessed using discrete-time event history analysis with multiple competing events. The risk group will include respondents with mobility limitation, which is defined as having any difficulty with the following tasks: 1) walking several blocks; 2) walking one block; 3) walking across the room; 4) climbing several flights of stairs; and 5) climbing one flight of stairs. At the beginning of each interval the risk group will be defined and potential outcomes will include: 1) stable mobility limitation (reference); 2) recovery from mobility limitation; and 3) attrited. Measures of the neighborhood characteristics will include both physical and social environment such as population density, street connectivity, proportion of non-vehicle commuters, neighborhood disadvantage, neighborhood age structure, neighborhood crime and segregation, and residential stability. Given the link between physical activity and neighborhood characteristics, interactions will be tested to determine whether physical activity moderates the relationship between neighborhood characteristics and recovery from mobility limitations.